I've worked on a number of arduino projects that involve tracking balloons/planes/boats. So far I've always used a GSM modem to send data in the form of SMS messages.

The catch is that above a few hundred feet, or out-of sight of the shore the modem stops working for obvious reasons. The solution seems to be to use a satellite modem. I've seen solutions in the past that are based on hardware-hacking of old satellite phones, but even this seems to involve expensive hardware, long contracts and expensive data rates. Just buying an iridium modem seems to be impossible, they only seem interested in selling large quantities at high prices with long contracts

I've come across this recently.....http://rockblock.rock7mobile.com/This seems to tick most of boxes, the modem is about £160, the subscription is £8 a month and it's 12 pence for 50 characters.

My questions are...Has anyone used this with an arduino? if so any problems?Is anyone aware of any similar or better options?

I'm not involved with it, but I understand that the UK High Altitude Society have a free collaborative radio tracking solution which might conceivably work for you. Otherwise, the conventional solution seems to be some sort of ham radio based system. I'm not surprised that satellite phone based solutions are expensive - it needs specialist hardware and the price you quoted seems quite a lot cheaper than I remember from Inmarsat.

I only provide help via the forum - please do not contact me for private consultancy.

Hello WorldRockBLOCK can send and receive short messages from anywhere on Earth with a view of the sky.Compatible with Windows, Mac and Linux computers (including Raspberry PI™) and many other platforms with USB or serial ports.

So far I've always used a GSM modem to send data in the form of SMS messages.

GSM modem -> 2G technologies

plan B. upgrade it to 4G Wimax, 30 to 40 megabit-per-second data rates, and 34 mb seem is the standard. Operating at the maximum range of 50 km (31 mi). to make 4G Wimax working with Arduino is easy. use Raspberry PI as shield connect with Wimax USB stick, and connect Raspberry PI via USB to Arduino. It works for me.

I need to send data from an Arduino data logger to remote SQL server, from remote places with little or no GSM / GPRS signal. Has anyone done something like this, successfully? The monitoring will be done in Africa though.

Just use a radio modem in 400 Mhz band UHF , with FSK or QFSK modulation or other, you do not get the high data rate like the modem but with a power amplifier of 6 to 10 W and a directive high gain antenna you cold receive the data with no problem from space. Of course you shod have a transceiver or the proper equipment, antenna, etc at the receiving side. See APRS ISS transmission from space for reference. Also there are radio repeater satellites for HAM radio use if you can send data threw thous. Up link in VHF and Down link in UHF and so on.